#define _CRT_SECURE_NO_WARNINGS 1
//#include<stdio.h>
//int main()
//{
//	char s[] = "\\123456\123456\t";
//	printf("%d\n", strlen(s));
//	return 0;
//}

#include <stdio.h>
//#define N 2
//#define M N + 1 //3   //2+1
//#define NUM (M + 1) * M / 2   //(2+1+1)*1/2
//int main()
//{
//	printf("%d\n", NUM);
//	return 0;
//}

int f(int n)
{
	static int i = 1;
	if (n >= 5)
		return n;
	n = n + i;//2,4,7
	i++;//2,3,4
	return f(n);
}
int main()
{
	int ret = f(1);
	printf("%d", ret);
	return 0;
}